1. Field of the Invention
The present invention relates to a stereomicroscope which includes an illuminating apparatus.
2. Description of the Related Art
In general, a stereomicroscope has a zoom portion and focus portion that can be separated from each other. Furthermore, stereomicroscopes have been variously modified to improve operational efficiency. A technique is known, in which a fiber illuminating apparatus comprising a fiber having a small tip is employed to illuminate a sample to be observed by the stereomicroscope.
The use of this fiber illuminating apparatus makes it unnecessary for the stereomicroscope to have large-sized light source heretofore. Thus, more space is available around the sample, which improves the operability of the stereomicroscope.
When the fiber illuminating apparatus is used, applying light to the sample, the loss intensity of light illuminating the sample will decrease if the light source unit including a light source applying light to the fiber is locate far away from the sample. Therefore, the sample cannot be illuminated enough to be observed well, unless the light source unit is increased in size and output. If a large, high-output light source is used, not only the cost of installing the light source unit will increase, but also the handling of the fiber will be cumbersome.
The light source unit that is used to achieve the illumination using the fiber illuminating apparatus is designed for exclusive use. Therefore, for example, when the sample is observed by transmitted illumination without using any fiber, a light source for transmitted illumination must be used in addition to the light source unit.
Furthermore, to observe a sample having an excessively low reflectance, more light is required. In this case, the fiber can hardly be used. However, if the fiber is not used, the light source unit for applying light through the fiber has to be held and adjusted so as to directly illuminate the sample.
Hitherto, various light sources must be prepared to illuminate samples well in various illuminating methods, respectively. Among the various illuminating methods are: a method that uses a fiber to perform oblique illumination; a method in which light is directly applied to the sample from the light source to perform the oblique illumination, without using the fiber; and a method that perform transmitted illumination.